Nitrogen Oxides and Nitroxyls

Abstract

The simplest representative of this class of free radicals is nitric oxide. In spite of the presence of a free valence, nitric oxide is considerably less active chemically than atomic hydrogen or chlorine, and, under ordinary conditions, does not recombine to form N2O2 molecules, apart from those cases where it is present as a liquid (bp, − 151.7°C) or solid (mp, − 163.6°C) [1–5]. On the basis of spectroscopic investigations of dimeric nitrogen oxide, it may apparently be ascribed a Π-shaped configuration [6–8]. Because of this, liquid nitric oxide possesses a high specific heat capacity, with a marked dependence on temperature, and a high entropy of evaporation.